北海银滩响应台风作用的动力地貌过程
喜扬洋(1988—), 男, 广西南宁人, 博士, 助理研究员, 从事海岸动力地貌相关研究。email: |
Copy editor: 姚衍桃
收稿日期: 2021-07-28
修回日期: 2022-01-08
网络出版日期: 2022-01-19
基金资助
国家自然科学基金重点项目(41930537)
广西科学院基本科研业务费资助项目(2020YBJ704)
Morphodynamic processes of the Yintan Beach in response to typhoon
Copy editor: YAO Yantao
Received date: 2021-07-28
Revised date: 2022-01-08
Online published: 2022-01-19
Supported by
National Natural Science Foundation of China(41930537)
Fundamental Research Project of Guangxi Academy of Sciences(2020YBJ704)
极端高能事件影响下的海滩动力地貌过程直接关乎岸滩稳定及海堤安全。本文基于2020年16号台风“浪卡”前后北海银滩顺直岸段的剖面高程及表层沉积物等资料, 探究了中等潮差的顺直响应台风作用的地貌变化机制。结果表明: 1) 台风后海滩地貌表现为冲流带的大型沙坝消失, 后滨沙丘-滩槽体系被削平, 滩面坡度趋于平缓。2) 银滩沉积物均以中砂、细砂和极细砂为主, 三者占比超过95%; 台风后, 高潮位带沉积物变细, 低潮位带沉积物变粗, 沙坝附近则出现粗细交错式变化; 银滩中高潮位带滩面响应台风过程的特征与强潮型海滩相似, 呈现消散型海滩的特征, 而低潮位带滩面则因大型沙坝的作用而呈现弱潮型海滩特征。3) 台风期间波浪是影响海滩的主要动力因素, 海滩地形影响了近岸水动力的表现形式, 从而改变了沉积物的粒径分布。
喜扬洋 , 王日明 , 冯炳斌 , 陈波 . 北海银滩响应台风作用的动力地貌过程[J]. 热带海洋学报, 2022 , 41(4) : 97 -104 . DOI: 10.11978/2021097
The beach morphodynamic process under the influence of extreme high-energy events is directly related to coastal stability and seawalls safety. Based on the profile elevation and surface sediments of the Yintan Beach collected before and after the 2020 16th typhoon “Nangka”, this paper explores the mechanism of morphological changes of a meso-tidal beach in response to typhoon actions. The results show that: (1) In post-typhoon period, the beach morphological changes are manifested by the disappearance of a large sand bar and the flattening of the bar-trough system, leading to a more gentle beach slope; (2) Sediment in Yintan Beach is mainly medium sand, fine sand and very fine sand, which account for more than 95%; The sediment grains become finer in the high tide zone and coarser in the low tide zone, while both increase and decrease in sediment grain size can occur near the sand bar; The morphodynamic process of mid-to-high tide zone of the Yintan Beach in response to a typhoon is similar to that of a macro-tidal beach, which is characterized by dissipative condition. However, the morphodynamic process of low tide zone of the Yintan Beach behaves like a micro-tidal beach due to the existence of a large sand bar; (3) During the typhoon, wave is the main dynamic factor affecting the beach, and the topography affects the manifestation of nearshore hydrodynamics, thereby changing the grain size distribution of sediment.
图1 台风“浪卡”路径(a)和采样剖面地理位置(b)图a基于国家测绘地理信息局标准地图服务网站下载的审图号为GS(2021)1487的标准地图制作。图b基于ESRI卫星影像绘制, 其中放大图中的黑线表示银滩的观测剖面 Fig. 1 Path of typhoon “Nangka” (a) and geographical location of the sampling profiles (b). The black line in the figure (b) represents the observation profile of the Yintan Beach |
图2 台风前后剖面的相对高程变化图中方点和圆点分别代表台风前(2020年10月13日)和台风后(2020年10月19日)的采样位置; 垂直虚线将剖面分成后滨、前滨上、前滨中、前滨下和冲流带; 箭头指向点(P0—P5)为绘制沉积物粒度累积概率曲线的代表点 Fig. 2 Relative elevation changes of the profile before and after the typhoon. The square and circle points in the figure represent the sampling positions before the typhoon on October 13th, 2020 and after the typhoon October 19th, 2020, respectively; The dashed line divides the profile into backshore, foreshore and other parts; The red arrow points represent the cumulative frequency curves of sediments |
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